Rail anchor



July 11, 1950 A. FL FIFIELD 2,514,601

RAIL ANCHOR Fiied Feb. 21, 1946 2 Sheets-Sheet 1 Patented July 11 1950 Ame canifi company;element};

Applicationaliebltuary z1, 1946;;Serial No.,649,1505;

11 v My invention relates to tworpi ee-xaii,anchors ofv1the, Stead-, type- :andt more -partieulg nl ,"invalvesan improvement inthet-pre-assembledttype.. ofifsteadl rail anchors:Which= ,is,exen plified. Joy 7 hee iselpsur s; of- .Unit.e States et ers vLlia ntw 5 v No -2,0223% I to- 19 W,- Coopen issued; Deeemher" 3, 1935.

Commonly, ear1ie r, -ty,pes .of. Steam? retiLa-nchors compr'ised-m ehannelrshaped clamp mem eryhav naits-arms notch d nwandly-; rom for: wand;- edge -topr0vide.i1ppert and lower glawsp. adapted to-ernbraee one-flw epfa rail base a provided; with a, .Web converging1y upwardly; dined-relative towthe planel ofIthe rail base gg gj ngt surfapes sofflthe lower; Jaws, and a 1001 sitt m a ehme ber comprisin rai qn tup arm erm na ingtfor mnd y n n p rned hQQkJ. ah ts rear-port o eing urvilinear y ip he istqr agrelatively short lowerarm directed, con'ger'gin'g lm q cwa'rd yand upwardlxt wards. an,.inte .tmdia e 0 p .t Qn,;.of the mm arm,..andl the lower su t'f 'q fiirthet hortarmvbeins adapted-to rest upq 'u h' upperrsu'rkfaceoith amp member Web: a1 such anchors, the retaining spring member "b1 n g f rmedrt mmua r p-0t t ened sp steel, was of lessetwidththan the spgtfoe betweenthe inter;- spsaedfl hanna garms, soethat. the anchor em; here s." re -assemb le d.only ,after the clgm gghengher was afiixed to the rail flange.

' The looped retainingspring of said priory-rail aneh'ors by Virtue of its looped formproviding a gigeetover-e ll length and its inherifen't ability tore; sili'ently flex under the varying conditions'l-Of epplieetio'nuse has, in the past; iarg iy contri b u'ted tothe popularity of-such arichors 'In-the said, hatented 're-assem-b' 'd Stead-- anchors-,- the means provided for main? taining the clamp andspring-members--in 'pread jiis ted relative positions; ready for -unitary-gppi ication to a. mi] base'residedin-providing eaeh 'of' both" arms with an intermediately disposed sdbwe-embr c e hewch esl ipeq 1 Q hQr Qt DriI mA -Q IW t i sechgaa;c onst ?uotigntwe seyyed gh 1313,05: affordingaunitary pie-assembl n Y v retainer-spring;rmernh gsi bu atthe di a d ar se dents; ac hiew tiv rtttheeatly, pe 0 t ,ad""

1 1., ie pert; asrres tediromj of aretaining s "ringh ggle .fro'm. 2 t m1; W'ho s mal ifeqt iz len ths e lly abgutt widthtoithi rai b' e, l v.

considexable port pn pf u hvlen imm bi zed t ub ntial d i 'e u silient y fi ctiv len hz In the anchor of my present"inyentipmthe; upper arm portions of the channel mp air so skewed relative to-the -lowerportion theltth i The rail -"ahehor of' ;--;my inVehtibnis thuse-nbt k only one adapted: to a cl'i'ieve a re a tory' ssemt bly of the p a r'ts'- i1 1'-=ope1 ative relsition tooneeans. other' 'to eif-"ee't a- -unita ry strueture aLda'pted for shipment, -roiigh -h'etndling; s and application: to a? ratll as a unit without additional relative :rea'd p justmentofitsememhers; but also is' adapted to effect such a,:umtaryLstmi'ettlre in a amalnner will not sinterferemithfree.:nesilieht idbfletiQfi-Ebfi thBnVBIT-iO'IiS ip'afrtsl 2o the..- looped aspringi member: during -."ap1o1iic'a;tt0m 01111181 anchor tdithe rail: non, thereafter during the various operativenoon di-r-zi ttons of use: I

yvv rtue, i mxcpres ntzmv mfiqnr a lirp n s ofi heis r nsgmemhe os g nd att r t 3 arms with the exception of one point at the two sides of a rearmost portion of the long arm is free of lateral compressive engagement by the inner surfaces of the channel arms.

An object of my invention therefore is to provide an improved preassembled Stead type rail anchor wherein no restraint against deflection of the long arm of }the looped spring retaining member is occasioned as a result of an improved 'construction whereby a preassembled two-piece anchor is achieved, the benefits of preassembling being thus achieved without loss of resiliency of said spring retaining member.

Another object of my invention is to provide an improved form of a preassembled Stead typev rail anchor wherein the provisions made for preassembly are efficiently effective andatthe same time without loss of operative efiiciency due to the provision of the operative elements relied upon to accomplish such preassembly.

Other objects of my invention and the invention'itself will become more apparent to those skilled in the art to which my invention apper tains by reference to the accompanying drawings which illustrate a single embodiment of my invention wherein:

' Figure l is a view in side elevation of the rail anchor of my invention applied to a rail base, the bottom being shown in transverse vertical section.

Fig. 2 is a pictorial view of the two-parts of the anchor in Fig. 1, in assembled relation, ready for application to a'rail base.

. mg. 3 shows, in tilted view, pre-assembled anchor parts in an initial stage of application to the rail base, the view otherwise being as in Fig. 1.

Fig. 4.- is a top plan view of the parts as shown inFig. 2.

Figs. 5 and 6 are respectively rear andfront elevational views taken from the respective planes -0 and dd, indicated in Fig. 4.

Referring more particularly to the drawing, ll designates a railroad rail having the usual base flanges l 2 and I3, and Fig.1 shows my improved rail anchor comprising a clamp member [6 and a. spring retaining member I! therefor, applied to said base flanges.

The spring member is. formedof a preferably 4 ber and two upstanding arms 26 each notched in a forward edge, as at 21, to afford upper and lower jaws adapted for reception of a rail base flange, such as the flange l2. The vertical depth of the notches is preferably such that the thinnest rail base flange for which the clamp is adapted willloea close fit in the notches without bottoming. Q j 1 Preferably, "the lower jaw surfaces 28 provided by the lowermost edge of the notches 2.! lie in a plane which is disposed at a substantial angle ."tothe plane of the clamp web 25, the upper jaw surfaces 29 provided by upper edge portions of the notches are disposed at such an angle to said lower-jaw surfaces, as to grippingly engage a rail base hanger-.0 which said jaws are applied, initialflatbar of spring metal bent flatw'i se intermediate lower arms terminate in upwardlyturned hook portions-2| and 22. The long arm is formed with a reversely curved portion 23 adjacent the loop and a slightly downwardly bowed portion 24 between the reversely curved portion 23 and. the upstanding hookv 2l,.the bowing preferably being such that said portion 24 of the long arm curves downwardly toward and then-upwardly away from the end of the short arm. -The short arm may be substantially straight between the loop [8 and the hook 22 and lies in such angular relation to the long arm that the tip of the hook 22 is normally spaced below the long arm, when the member is relaxed, as shown in Fig. 3. The two arms and'jthe loop constitute a resilient structure, wedge-shaped in its vertical aspect of which the loop constitutes the butt, or large end- The clamp member is channel-shaped, as shown in Fig. 2, being preferably formed by bending a flat sheet of metal, to provide a web portion 25 forming a seatfor the spring mem- 'stantially inwardly from the flange edge, thereby to minimize any tendency to weaken the edge portions of said flange.

The lower rearward end of the web 25 is preferably provided with an upward projection 33,

which may be most conveniently'forrned by upward stretching" displacement of the metal of the web which is disposed midway between the junction of said web and the channel arms.

The channel clamp member of my invention differs from prior constructions in such manner as to efficiently adapt it for preassembly with the retainer spring but without resultant immobili zation of the spring action of the clamp enclosed portion of said spring. This, I have achieved by effecting front-to-rear convergence of the opposing inner surfaces of the upper portions of the two channel arms only in what I term the upper zone which comprises all portions of the free ends of the two arms which are disposed above the line A-A' of Fig. 1. The rearward portions of the opposing surfaces of the said two arms disposed in said upper zone are therefore disposed more closely together than the opposing surfaces thereof which are relatively disposed nearer the front edges of said arms.

The line A--A ofFig. 1 which is preferably parallel to and spacedsomewhat below the plane of the lower jaw, gripping surface, taken in conjunc tion with the line B-A defines an acute angle which includes a. shoulder 32'of gradually diminishing depthand up-and-down extent which is of greatest depth and extent at the rearmost edge portions of the channel arms and which preferably terminates in the region of the junction of said lines, said shoulder 32 being interposed between upper and lower zone portions of the'channel arms and affords an off-setting-junction between the lowermost relatively parallel arm portions 26l and the uppermost relatively front-to-rear converging portions 262.

The clampmember of my present embodiment therefore is in channel form with its arms presenting a pair of preferably substantially straight and parallel front edges, though interrupted by the-notches 21, and a pair of relatively straight and parallel lowermost rear edge portions which are disposed below the shoulder 32 with a pair of inwardly offset rear edge upper portions, ,dis posed above said shoulder.

The rail anchor of the described embodiment is therefore of the pre-assembled Stead type and employs the conventional Stead type of rearwardly-looped resilient flat bar steel spring retaining member shown generally at H, wherein lfl-joins the pair of relatively forwardly converg- 5 ing: relatively long and short; spring.-;-arms L2. 19 and 2.0.

'I'hespriorconventional type of pro-assembled Stead rail anchor is best typifiedibyitheanchor disclosed in the. aforesaid. Cooperzpatent.

I The clamp memberhereof is distinguished from said prior anchor inthat only. the opposing innersurface portionsoi said. :clamp. arms, which are nearest-the rearmost edges oflthe arms :and which arerllocated in. an *upperportion of .said arm; are converged. to a maximum.degree.

;3I'I1.;this 'inanner the portions :2 6250f. the. innersurfaces 'oftthe. arms I6, whichsaramost closely relatively .interspacedp are lo'catedvadjacent the rearnrostxedges of the clamp arms .lifi onlygin'portionsuthereof .which are located: at least .as' .far distant ;from .the predominant. planexof. the z-w'eb 25,- and excluding the :web tongue; 233,5. as are the-most forward-portions. of stherl'ower .zjaw; surfaceszs28.

\ The width; of the .bar from" which.;the"spring retaining: member. is vformed is. :suohthat swhen positioning the :spring retaining member. between the clamp arms,- relatively. opposite. lateral: edge portions. of thespring arm Ilwedginglyengaged untilthe most closely converged, relatively. eonfronting: inner surfacestofthe clamp arms in those portionsof said clamp.:armsareradjoining the rearmostedges of the-.channelarmsyin saidupper: :zone, whereby .the ..arms will resultantly be forcibly spread apart an .amountzgequal."to;, the excess of width of the interposed portionspf the springmember over the normal distaneebetween the converged rearmostportionsxof the inner "surfaces of the two arms in said upper-zone.

.xInthe present embodiment the :spring. bar is substantially of uniform length throu hout, and while such uniformity ;of width is. preferred, my inventionis not limited to preciseuniformity-of .thespring bar width.

.To-achieve preassembly of the two anchor parts at the factory, this may bebest accomplished byreither introducing-the hooked end ,of the long .armzof the retaining member betweenthe clamp aarmsclose to the web from the'rearmost side .of I

;the.clamp, and then pressing the retainingmem- .ber forwardly in such manner as to projectthe .rail fiange retaining hook 2| into the approximate plane of the lowermost jaw gripping suriaces, or,if desired, a midportionof the lower short arm 29 of the retaining member may (be hand-placed between the upper and forward corners of the clamp memberarms with said short arm; preferablyv disposedv in a plane, parallel .to

that of the lower jaw gripping surfaces and then applying thepower of a press to theupper side of the long arm of the retaining member in such a, direction as to accomplish thesame positioning of the spring member within theclamp as, according to the first method. I

.The. transversely resiliently effected grip .by the converged rearward inner surface of the aforesaid upper portions ofthe arms just above theshoulder 32 is sufficient to hold the two parts :rigidly in the. established relation against any force tending to alter such relation which would ordinarily be encounteredin' hand shippingand distribution for application to a rail base. ...'For.pra'ctical purposes, the two parts of the anchor are maintained in unitary. relationship readyeforapplication to a vrail base -yet, since ,theretainer spring is only gripped ata single extremely short portion of its .lengthby; thetclamp side.arms,..the twoparts are ,capable .of relative movement for; adjustment. to. a rail; and. all -;por-

tionsoftheretainin rspring.areas welradapted torrsuch readyiflexi-ng of its variousmmtionsasin the :.:-.ca'se:..c.of the early: ,type. of :non assembled ifisteadt anchors; and throughout all of the varyingiconditions; ofactual use, the various parts of the spring retainingmemberaare capable-of being flexeds without..;undue-restraint. by. thev one. point lateral-:ensagement of theclamp sidearmsiwith the .side edges aof said retaining member.

.Inthe yfactoryrassemblm the. spring member :is advanced through the. :clampmember untilthe endmf. the iong arm hook -2 Iris approximately flushwith-:the surfaces; :28 of 'the clamp jaws, .as shown-.;--in-:;1 ig.-3. The vertical and horizontal grip of- -theiclamp member on the spring member is sufiic-ient -;-to holdthe two parts rigidly in the established relationsagainst greater -force;.tendmg {1110 alter. the relation than will ordinarily-the encountered in handling, shipment and distributionzfor application. In short,.the twoqiipartsware so rigidly related that for all practical purposes :othandling, they areas much a unit as, ifformed ota si nglepiece of metal. 'YetIthe parts ofthe .unit are 'capable of relative i'movement-for adjustment to a. rail, or, ;ifnecessary, forgseparation.

The wedging icammingeffect ofthe converging surfaces-32 causes the spring member-to assume the :relation-to the clamp member. illustrated :in

Flier-3 duringiinsertion'in the clamp member and also servesto maintain this relation which isthat desiredas apreliminary to application to a-rail. Thesem-i-rigid factory assembled unit, shown in Fig.: 3,-.isappliedto a mail by manually passing'the p iojecting spring member arm 2 4. beneath arail whileyholding the clamp,- so that notches thereof receive the edge of: one .railwbase flange, one arm 101, the clamp. member being held in close engagement with the side: ofatie. 'Thismanual application may be effectedwithout resistance to sl-ightlylmorethanthe extent :shownin Big. 3, that-is,'-.until theupward swingpf. the advancing end-of the-unitcaused by the notchestaking-posi- -tion--;on..one,.-base flangebrings the endof the hook.-2|.-.against the bottomof the other-.--base flange close :totheedge thereof. Theeapplicationais icontinued forcibly, as 'by strikingtheprojecting 100p l8 with a hammer.

Thisapplicationof force urges the spring member to advance through the clamp-and is.-a1so transmitted to the ;clamp principally-Joyfnictional engagement of .thewlower arm 29 withxthe inclined web of the clamp. Thetransmission of force to the-clamp ,beingentirely beneath therail, .thelowerendof-the clamp is swung-inwardly and upwardly: about apivotalpoint. at theengage mentsof the corners L with the upper surface of the-base-flange. and. causes the clamp to move to its'fi-nal relationto the rail, as 'lshowntin *Fig. .1. w This swingingmovement relievesrthe tendency 'of the ,clampcorners 3| to bite. into the flangelan d, if. desired,-.further grelief may-be obtainedt'byia slight chamfering "of: the corner 3 I :Asth'espring member advances through theclamp, its looped end :is subjected to 'vertical. compression "both; by reason of its-wedging action between theconverg ing web and offsets and by. reason of its; upward movement on the inclined 'web,=,brin'ging, the top of :the loop into engagement with .the bottomwf st-herail base. At the sametime,-the aforesaid upward-swing of'the clamp member bodily raiseszth'e spring member. and -thrusts. thehook 21 against 'thet-bottom- ;of-the rail base'flange l-3=xandzcauses the long. arm of. the spring; member .to :be 1 flexed withstraighteningtendencm; so -;that-;;by.- the some bined compression aiid arm flexion, the space between the short arm hook 22 and the long-arm is closed and thereafter upward movement of the hook 22 due to climbing on the inclined web and to upward swing of the clamp is transmitted in its entirety to the long-arm. l

1 It has been stated that movement is transmitted from the spring -member to the clamp member chiefly through the bottom arm of the spring member, and this is due to the increasing inclination of the web, as the clamp swings, andto the fact that the upward swing for a time raises the inner ends of the offsets 32 at about the same rate that the upper arm of the spring member rises. As the spring member advances through the clamp, the resistance increases by reason of further'compression of the loop between the projection 33 and the bottom of the rail base flange l2 and also by reason of the increasing inclination of the web due to the inward swing of the 1 clamp.

- Before any very great increase of resistance is manifest, the point of maximum depth of the loop passes the top of the projection 33 and the loop commences to travel down the inwardly facing incline of the projection and by expansion maintains its contact with the bottom surface of the rail base flange [2. #This downward movement tends to offset the resistance to further advance due to the increase in the inclination of the spring path, and also tends to cause the entire spring member to swing in a vertical plane about its line of support at the inner edge of the web; so that the hook 2| isthrust upwardly against the bottom of the rail base flange'l3 close to the edge thereof with additional force and, as actual upward movement ofthe hook is prevented, the swinging tendency of the spring member-causes additional flexion of the arm I9 with further straightening tendency.

The combined advance of the spring member through the clamp and the bodily inward movement and inward swing of the clamp member as aforesaid cause the hook 2i to pass the edge of the rail base flange and to be raised into engagement with the edge surface of the flange by the upward swing of the spring arm and held by the tension thereof. p

A few taps directed against the upper rearward corners of the clamp member may then, if the spring member has been accidentally overdriven, cause it to recoil so that the hook 2l is drawn tightly against the rail flange edge.

The described structure involving inward spring pressure engagement between a very limited portion of the length of the spring arm disposed in the downwardly bowed portion 23 with cone-'- spondingly small areas of the most inwardly converged inner surfaces of the clamp arms, achieves applicants objective of eliminating substantial immobilization of the reactive spring action of said long arm 59 which previously has adversely affected the ability of the anchor to be retained in place upon a rail base under severe conditions of usage involving up-and-down movement of the rails when traversed by trains, said up-and-down movements sometimes causing the lower surface of the clamp to forcibly engage underlying road ballast materials and tending to turn the clamp, together with the spring IS, in a clockwise direction, as viewed in Fig. 1. Such momentary clockwise movement in the prior assembled Stead type of anchors has had the effect of depressing the hook 2| sufficiently to loosen said hook from its associated side of the railbase, and

in manycase's, under conditions of hard or frozen; substantially high road ballast underlying the rails, Stead anchors have become dislodged from the rail base.

In the present construction, however, the longer effective length of the spring arm i9 is sufficient to'maintain'the hook 2! in place, and dislodgement of. the anchor from the rail, under above described conditions, does not occur.

.So far as the mere semi-permanent assembly of the parts to resist'separation is concerned, the existence of the projection 33 is not material nor is this projection material to the establishment and maintenance of the desired relation of the parts for application purposes, since this elfect is produced by the relation of arm convergence to the pointsof support of the spring member on the web and, by suitably positioning or forming the converging arm surfaces, the desired efiect may be produced with any lower projection and ob-. viously, the height of the projection may be reduced to nothing. The projection is, however, to facilitate application by reducing the inclination of the path of the spring member.

Having thus described my invention, I am aware that obvious departures from the precise form of the illustrated embodiment of my invention may be made without departing from the spirit of my invention and such obvious departures are within the scope of my invention as defined by the claims.

I claim:

1. In a two-piece'rail anchor, the combination of a spring retainer member of substantially uniform width formed from a flat steel bar, said bar being bent to provide an uppermost long spring arm terminating forwardly in an upturned hook and a relatively short lower spring arm integrally joined to the rear end of the long spring arm and extending forwardly and upwardly to dispose its free end below a medial portion of the long spring arm, a U shaped clamp formed of flat steel to provide a pair of upstanding clamp arms and a webinterconnecting thelowermost portions of said clamp arms, the lower end portions of said clamp arms being disposed substantially arallel to each other and another more upwardly disposed portion of both said clamp arms being inwardly'skewed in the rearward direction to cause the relatively opposing inner surfaces of said clamp arms which are disposed nearest the rear edges of such relatively upper clamp arm portions to be more closely interspaced than any other opposed inner surfaces of the clamp arms,

each of said clamp arms being correspondingly notched inwardly and upwardly from an intermediate portion of their forward edges to afford, by the upper and lowernotch edges, a pair of relatively divergent upper and lower rail-base flange jaw surfaces, said lower notch edges being disposed in a plane which is rearwardly divergent withrespect to said web, the said opposed most closely interspaced inner surface of said clamp arms being disposed rearwardly of said notches and below the rearwardly extending plane of said lower notch edges,'said retainer being insertable between the clamp arms with a rearwardly disposed portion of the upper arm wedged tightly between said clwely interspaced opposed inner surfaces of said clamp arms. and all other portions of the retainer member which are disposed between said arms, below said plane, and above said web, being free of lateral pressure engagement by any portion of said clamp'arms the said hook end of the long retainer arm being extended forwardly from between said clamp arms, whereby the clamp and retainer members are unitarily interconnected for application to a rail base, said notches adapted to embracingly receive one flange of the rail base, and said long arm hook adapted to be snapped upwardly over the lateral edge of the other rail base flange, in response to driving pressure applied to the rearmost portion of said retainer.

2. In a rail anchor substantially of the twopiece type comprising the combination of a looped substantially resilient spring member of substantially uniform width having a long upper spring arm terminating forwardly in a upturned hook, a shorter lower spring arm extending forwardly in upwardly converging relation to a medial portion of the upper arm, a rearmost C-shaped armconnecting loop interconnecting said spring rms, with a channel-shaped clamp, said clamp comprising a pair of upstanding arms and a web connecting the lower portions of said arms, and both arms being so correspondingly notched inwardly and upwardly from an intermediate portion of their forward edges as to provide a pair of rearwardly convergent upper and lower notch edges respectively affording relatively upper and lower jaw surfaces, said lower jaw surfaces being disposed in a plane which is in forwardly convergent relation to said web, and said clamp arms comprising relatively upper and lower portions which are respectively successively disposed between said plane and said web, the said lower portions being substantially parallel and said upper portions being rearwardly convergent toward the rearmost edges of the clamp arms whereat the opposing inner surfaces of the said upper portions of the clamp arms which are adjacent the rear edges thereof and disposed adjacently below said plane are in more closely interspaced relation to each other than are any other opposing portions of said arms which are disposed between the plane containing said lower jaw surfaces and said web, said most closely interspaced opposing inner surface portion of the clamp arms being initially disposed more closely together than the width of the spring member, whereby said spring member and clamp may be pre-assembled with the looped portion of the spring member being forced between said clamp arms below the said plane of the said lower jaw surfaces, whereby said clamp arms will be resiliently spread apart by the interpositioning of a, substantiall short portion of the spring member, which is disposed in the general region of juncture between said connector and long arm portions, between said most closely interspaced and rearwardly disposed inner surface portions of the said relatively upper portions of said clamp arms, said clamp arms by resilient retractive effort tightly frictionally holding the spring member and clamp together for unitary application in the usual manner to a rail base, whereupon with one flange of the rail base being received between the sets of upper and lower clamp jaw surfaces and with driving blows applied against the rearwardly exposed portion of the connector portion of said spring member, said upturned hook is adapted to be snapped upwardly over the opposite rail base flange edge of the rail base, and said spring member being otherwise, than aforesaid, free of lateral frictional engagement with any other inner surface portions of said clamp arms.

3. In a rail anchor of the two-piece type, a steel spring retaining member having a forwardly converging, rearwardl interconnected, pair of relatively superposed spring arms of which the lower spring arm is the shorter and is forwardly upwardly inclined toward a medial portion of the upper spring arm, a U-shaped clamp member having a pair of upstanding clamp arms and a web interconnecting the lower ends of said clamp arms, said arms being rearwardly and upwardly notched from a medially disposed portion of their forward edges in such manner as to provide for each arm a pair of forwardly divergent relatively upper and lower notch edge surfaces which are adapted to afford a pair of relatively superposed cooperative rail base flange embracing jaw surfaces, said clamp arms alike having relatively opposing inwardly displaoed inner surface portions of substantially small area which are located substantially adjacent to rear edge portions of said clamp arms and substantially closely below a rearwardly extended plane which contains said lower jaw surfaces, all other opposing inner surface portions of said clamp arms, located below the said plane, being relatively more laterally interspaced than said inwardly displaced opposing irface portions thereof, rearwardly disposed portions of said retaining member being adapted, during pre-assembly of the members and also during unitary attachment of the assembled retaining and clamp members to a rail base, to be laterally embraced by said clamp arms, said embraced portions of said retaining member being of such a uniform width that a tight wedging frictional engagement is effected only between said inwardly displaced inner surfaces of said clamp arms and relatively short opposite lateral edge surfaces of an upper rearwardly disposed portion of said retaining member, all other lateral surface portions of the retaining member which are disposed between said clamp arms being adapted to fit loosely between more widely interspaced inner surface portions of said clamp arms.

ALBERT F. FIFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

